VLADIVOSTOK, Russia (AP) — North Korean leader Kim Jong Un boarded his private train Friday and headed back to Pyongyang after directing some harsh criticism at Washington during his first summit with Russian President Vladimir Putin, saying the U.S. negotiated in “bad faith” when he met with President Donald Trump in Hanoi two months ago.

It was not immediately known why he decided to return from Vladivostok early. Putin, who indicated he may be interested in playing a bigger role in breaking North Korea’s standoff with Washington, had already left for a two-day meeting in Beijing.

The Kremlin intends to brief the U.S. on the contents of the summit as soon as the Russian delegation returns to Moscow, Deputy Foreign Minister Sergei Ryabkov told the RIA Novosti news agency. Putin said he will also brief Chinese leaders on his talks with Kim.

Before leaving Vladivostok, Kim visited a park near the headquarters of the Russian navy’s Pacific Fleet for a wreath-laying ceremony that was held two hours later than expected. Kim also had lunch with the local governor and businesspeople on the outskirts of town before going to the main railway station.

Following their talks on Thursday, Putin said Kim is willing to give up nuclear weapons, but only if he gets ironclad security guarantees supported by a multinational agreement.

Kim strongly criticized Washington for taking a “unilateral attitude in bad faith” at his February meeting with Trump in Hanoi said that caused the diplomatic standstill, North Korea’s state-run Korean Central News Agency said Friday.

He also told Putin the situation on the Korean Peninsula has reached a “critical point” and whether tensions resume will “entirely depend on the U.S. future attitude.”

The agency said Putin credited Kim’s diplomatic initiatives for stabilizing the situation surrounding the peninsula and accepted Kim’s invitation to visit North Korea at a “convenient time.”

No specific measures from the summit have been reported by either side and the leaders’ comments suggest there has been no significant shift in Kim’s basic position.

North Korea has all along contended that it needs its nuclear arsenal to defend itself against what it sees as U.S. hostility and wants concrete reassurances of its safety — including the removal of the American nuclear threat as an integral part of the denuclearization of the entire Korean Peninsula.

Trump has voiced hope that Putin’s involvement could help his efforts to get Kim to abandon his nuclear arsenal. But it could also complicate matters, since Moscow has been critical of sanctions on North Korea and has called on Washington to provide more security guarantees. After Thursday’s talks, Putin suggested the revival of a multilateral approach to the denuclearization negotiations. A similar approach, which Russia participated in, broke down in 2009.

Along with a statement of political support, Kim was also looking for some kind of economic support and possibly even a workaround for sanctions that will require more than 10,000 North Korean laborers in Russia to leave by the end of the year. The laborers are a major source of income for North Korea.

Putin said they discussed the issue and would find a solution taking into account “humanitarian” factors, though he didn’t say what that would be.

Motorists in the Russian port city breathed a sigh of relief at Kim’s departure. Traffic in the city of half a million had been severely disrupted since Kim’s arrival on Tuesday. Just like two days earlier, traffic was completely blocked in the city center during the send-off ceremony for Kim.

___

Talmadge, the AP’s Pyongyang bureau chief, reported from Tokyo. AP writers Nataliya Vasilyeva and Jim Heintz in Moscow, and Hyung-jin Kim and Kim Tong-hyung in Seoul, South Korea, contributed to this report.